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Known Traveler Number

General

Known Traveler Number (KTN)

A numeric identifier assigned to members of US trusted-traveler programs like TSA PreCheck and Global Entry, printed on airline bookings to enable expedited security screening.

Definition

A Known Traveler Number (KTN) is a numeric identifier issued to members of US trusted-traveler programs, including TSA PreCheck, Global Entry, NEXUS, and SENTRI. Travelers enter their KTN when booking a flight so that airline reservation systems can flag the booking for expedited security screening, shorter lines, no need to remove shoes or laptops, and reduced restrictions on liquids.

The KTN itself doesn't identify a specific program; it is simply the traveler's enrollment number, matched against TSA and CBP databases using the traveler's name, date of birth, and gender at the time of booking.

Formula

A KTN has no publicly documented checksum formula, it is a numeric identifier assigned during program enrollment, with length and structure varying somewhat by the specific program (TSA PreCheck vs. Global Entry vs. NEXUS/SENTRI). Structural validation focuses on:

  1. Confirming the value is numeric (KTNs do not typically include letters).
  2. Confirming the length falls within the plausible range used by TSA and CBP-issued numbers.

Because there is no mathematical check digit, a validator can only confirm plausible formatting, actual program membership can only be confirmed by TSA or CBP matching the number against the traveler's identity details.

Worked Example

A structurally plausible but entirely fictional example: TT2938471, though actual formats vary, Global Entry numbers are commonly presented as a purely numeric PASS ID rather than one with letters.

Key Things to Know

  • No checksum digit: format checks via the Known Traveler Number Validator only confirm plausibility, not actual enrollment status.
  • Tied to program membership: the number is issued upon enrollment in TSA PreCheck, Global Entry, NEXUS, or SENTRI, and expires when membership lapses (typically after five years).
  • Matched against traveler identity, not just the number: airlines validate a KTN together with the traveler's name, date of birth, and gender, the number alone is not sufficient.
  • Different from a passport number: a US Passport Number identifies a travel document; a KTN identifies trusted-traveler program membership for expedited screening.
  • Entered at booking, not check-in: the KTN must be added to the reservation (directly or via a stored traveler profile) before the boarding pass is issued to receive the TSA PreCheck indicator.
  • Not proof of identity on its own: unlike an SSN, a KTN is not treated as a general-purpose identity credential, its only function is expedited screening eligibility.

Related Terms

US Passport NumberUnited States Passport Book/Card NumberSSNUS Social Security Number

Frequently Asked Questions

Where does a Known Traveler Number come from?
A KTN is generated when a traveler enrolls in a US trusted-traveler program, TSA PreCheck, Global Entry, NEXUS, or SENTRI, and is issued by the relevant agency (TSA or CBP) once background vetting is complete. The same underlying number typically works across the airline booking systems that recognize any of these programs. Format plausibility can be checked with the [Known Traveler Number Validator](/known-traveler-validator/).
Does a KTN have a fixed number of digits?
No single fixed length applies universally, TSA PreCheck numbers (also called Redress or PASS ID numbers in some contexts) are typically numeric strings of varying length depending on the issuing program, unlike a strictly defined format such as a 9-digit SSN. This variability is why KTN validation focuses on plausible numeric ranges and length rather than a single rigid pattern.
Is a Known Traveler Number the same as a passport number?
No. A [US Passport Number](/glossary/us-passport-number/) identifies a specific passport document for international travel and border crossing, while a KTN identifies enrollment in a trusted-traveler program and is used to request expedited security screening for domestic and some international flights. Airlines ask for both separately when relevant.
What happens if I enter my KTN incorrectly on a booking?
If a Known Traveler Number doesn't match TSA's records for the passenger's name and date of birth, the boarding pass will not display the TSA PreCheck indicator, and the traveler will go through standard security screening instead. There is no penalty for an incorrect entry beyond losing the expedited screening benefit for that specific flight.
Can a Known Traveler Number expire?
Yes, KTNs are tied to program membership, which typically lasts five years for TSA PreCheck and Global Entry before requiring renewal. Once a membership lapses, the associated KTN no longer grants expedited screening until the traveler renews their enrollment.